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  <title>计算 e 的指数</title>
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  <div id="layout-content"><div id="function.exp" class="refentry">
 <div class="refnamediv">
  <h1 class="refname">exp</h1>
   <p class="verinfo">(PHP 4, PHP 5, PHP 7, PHP 8)</p><p class="refpurpose"><span class="refname">exp</span> &mdash; <span class="dc-title">计算 <strong><code>e</code></strong> 的指数</span></p>

 </div>
 <div class="refsect1 description" id="refsect1-function.exp-description">
  <h3 class="title">说明</h3>
  <div class="methodsynopsis dc-description">
   <span class="methodname"><strong>exp</strong></span>(<span class="methodparam"><span class="type">float</span> <code class="parameter">$num</code></span>): <span class="type">float</span></div>

  <p class="para rdfs-comment">
   返回 <strong><code>e</code></strong> 的 <code class="parameter">num</code> 次方值。
  </p>
  <blockquote class="note"><p><strong class="note">注意</strong>: 
   <p class="para">
    用“<strong><code>e</code></strong>”作为自然对数的底数，大约为 2.718282。
   </p>
  </p></blockquote>
 </div>

 <div class="refsect1 parameters" id="refsect1-function.exp-parameters">
  <h3 class="title">参数</h3>
  <p class="para">
   <dl>
    
     <dt>
<code class="parameter">num</code></dt>

     <dd>

      <p class="para">
       要处理的参数
      </p>
     </dd>

    
   </dl>

  </p>
 </div>

 <div class="refsect1 returnvalues" id="refsect1-function.exp-returnvalues">
  <h3 class="title">返回值</h3>
  <p class="para">
   &#039;e&#039; raised to the power of <code class="parameter">num</code>
  </p>
 </div>

 <div class="refsect1 examples" id="refsect1-function.exp-examples">
  <h3 class="title">范例</h3>
  <p class="para">
   <div class="example" id="example-3092">
    <p><strong>示例 #1 <span class="function"><strong>exp()</strong></span> 例子</strong></p>
    <div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB">&lt;?php<br /></span><span style="color: #007700">echo&nbsp;</span><span style="color: #0000BB">exp</span><span style="color: #007700">(</span><span style="color: #0000BB">12</span><span style="color: #007700">)&nbsp;.&nbsp;</span><span style="color: #DD0000">"\n"</span><span style="color: #007700">;<br />echo&nbsp;</span><span style="color: #0000BB">exp</span><span style="color: #007700">(</span><span style="color: #0000BB">5.7</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">?&gt;</span>
</span>
</code></div>
    </div>

    <div class="example-contents"><p>以上例程会输出：</p></div>
    <div class="example-contents screen">
<div class="cdata"><pre>
1.6275E+005
298.87
</pre></div>
    </div>
   </div>
  </p>
 </div>

 <div class="refsect1 seealso" id="refsect1-function.exp-seealso">
  <h3 class="title">参见</h3>
  <p class="para">
   <ul class="simplelist">
    <li class="member"><span class="function"><a href="function.log.html" class="function" rel="rdfs-seeAlso">log()</a> - 自然对数</span></li>
    <li class="member"><span class="function"><a href="function.pow.html" class="function" rel="rdfs-seeAlso">pow()</a> - 指数表达式</span></li>
   </ul>
  </p>
 </div>

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